Magnetic field solenoid

Abstract

The solenoid includes an electrical coil having a central opening in which is fixedly located a rod formed of a material of the type capable of being magnetized when in a magnetic field. A plunger is supported for movement toward and away from one end of the rod. A permanent magnet is supported by the plunger. In one embodiment the permanent magnet is located such that the plunger and permanent magnet are held next to the coil when the coil is in a deactivated condition. When the coil is activated, the magnetic field produced by the coil repels the permanent magnet and hence the plunger away from the coil. The polarity of the permanent magnet can be reversed in position such that normally the permanent magnet and hence the plunger are normally repelled away from the rod end when the coil is in a deactivated condition. When the coil is activated in a given manner, the magnetic filed of the coil pulls the magnet and hence the plunger next to the coil. In another embodiment two permanent magnets are attached to opposite ends of a plunger of the type unaffected by a magnetic field to form a push-pull type of solenoid.

I claim: 
     
       1. A solenoid, comprising: a housing comprising a surrounding wall forming an opening extending between first and second ends with first and second end walls coupled to said first and second ends of said surrounding wall respectively forming an enclosed cavity,   an electrical coil fixedly located in said enclosed cavity of said housing,   said electrical coil having a central opening extending therethrough with said central opening having a central axis,   said electrical coil having first and second ends with said first end located near said first end of said surrounding wall of said housing,   said second end wall of said housing being spaced from said second end of said coil,   a rod formed of a material capable of being magnetized when located in a magnetic field,   said rod being fixedly located in said central opening of said electrical coil and having an end extending to a position near said second end of said electrical coil,   a plunger comprising a permanent magnet and support means for supporting said permanent magnet for movement in the space between said second end of said coil and said second end wall of said housing along a path in line with said central axis in opposite directions within said enclosed cavity to locate said permanent magnet in first and second positions wherein said end of said rod will be located in the magnetic field of said permanent magnet and in the magnetic field produced by said coil when energized such that when electrical power is applied to said coil, a magnetic field is produced by said coil which moves said plunger in a direction along said path to locate said permanent magnet in said second position spaced away from said second end of said coil and when the electrical power to said coil is terminated, the magnetic field produced by said permanent magnet moves said plunger along said path in a direction to locate said permanent magnet in said first position near said second end of said coil,   said second end wall of said housing comprises an opening formed therethrough,   said support means being moveably supported in said opening of said second end wall of said housing,   said plunger comprises means for engaging said second end wall of said housing when said permanent magnet is moved to said second position for preventing movement of said permanent magnet beyond said second position,   said plunger being the only movable means of said solenoid.   
     
     
       2. The solenoid of claim 1, wherein: said magnetic field of said permanent magnet is the only force that moves said permanent magnet from said second position to said first position.   
     
     
       3. The solenoid of claim 1, wherein: said opening of said surrounding wall is cylindrical in shape having a given diameter wherein the space between said second end of said coil and said second end wall is cylindrical in shape having a diameter substantially equal to that of said given diameter.   
     
     
       4. The solenoid of claim 1, wherein: said support means extends through said opening of said second end wall with an end extending beyond said second end wall when said permanent magnet is located in said second position,   said end of said support means when extending beyond said second end wall is unenclosed.   
     
     
       5. The solenoid of claim 1, comprising: a source of electrical power, and   a switch for connecting and disconnecting said source of electrical power to and from said electrical coil,   said source of electrical power and said switch being located outside of said housing,   said switch being the only means for connecting and disconnecting said source of electrical power to and from said coil.   
     
     
       6. The solenoid of claim 2, wherein: said opening of said surrounding wall is cylindrical in shape having a given diameter wherein the space between said second end of said coil and said second end wall is cylindrical in shape having a diameter substantially equal to that of said given diameter.   
     
     
       7. The solenoid of claim 2, wherein: said support means extends through said opening of said second end wall with an end extending beyond said second end wall when said permanent magnet is located in said second position,   said end of said support means when extending beyond said second end wall is unenclosed.   
     
     
       8. The solenoid of claim 2, comprising: a source of electrical power, and   a switch for connecting and disconnecting said source of electrical power to and from said electrical coil,   said source of electrical power and said switch being located outside of said housing,   said switch being the only means for connecting and disconnecting said source of electrical power to and from said coil.   
     
     
       9. The solenoid of claim 6, wherein: said support means extends through said opening of said second end wall with an end extending beyond said second end wall when said permanent magnet is located in said second position,   said end of said support means when extending beyond said second end wall is unenclosed.   
     
     
       10. The solenoid of claim 6, comprising: a source of electrical power, and   a switch for connecting and disconnecting said source of electrical power to and from said electrical coil,   said source of electrical power and said switch being located outside of said housing,   said switch being the only means for connecting and disconnecting said source of electrical power to and from said coil.   
     
     
       11. The solenoid of claim 9, comprising: a source of electrical power, and   a switch for connecting and disconnecting said source of electrical power to and from said electrical coil,   said source of electrical power and said switch being located outside of said housing,   said switch being the only means for connecting and disconnecting said source of electrical power to and from said coil.   
     
     
       12. The solenoid of claim 3, wherein: said support means extends through said opening of said second end wall with an end extending beyond said second end wall when said permanent magnet is located in said second position,   said end of said support means when extending beyond said second end wall is unenclosed.   
     
     
       13. The solenoid of claim 3, comprising: a source of electrical power, and   a switch for connecting and disconnecting said source of electrical power to and from said electrical coil,   said source of electrical power and said switch being located outside of said housing,   said switch being the only means for connecting and disconnecting said source of electrical power to and from said coil.   
     
     
       14. The solenoid of claim 4, comprising: a source of electrical power, and   a switch for connecting and disconnecting said source of electrical power to and from said electrical coil,   said source of electrical power and said switch being located outside of said housing,   said switch being the only means for connecting and disconnecting said source of electrical power to and from said coil.   
     
     
       15. A solenoid, comprising: a housing comprising a surrounding wall forming an opening extending between first and second ends with first and second end walls coupled to said first and second ends of said surrounding wall respectively forming an enclosed cavity,   an electrical coil fixedly located in said enclosed cavity of said housing,   said electrical coil having a central opening extending therethrough with said central opening having a central axis,   said electrical coil having first and second ends with said first end located near said first end of said surrounding wall of said housing,   said second end wall of said housing being spaced from said second end of said coil,   a rod formed of a material capable of being magnetized when located in a magnetic field,   said rod being fixedly located in said central opening of said electrical coil and having an end extending to a position near said second end of said electrical coil,   a plunger comprising a permanent magnet and support means for supporting said permanent magnet for movement in the space between said second end of said coil and said second end wall of said housing along a path in line with said central axis in opposite directions within said enclosed cavity to locate said permanent magnet in first and second positions wherein said end of said rod will be located in the magnetic field of said permanent magnet and in the magnetic field produced by said coil when energized such that when electrical power is applied to said coil, a magnetic field is produced by said coil which moves said plunger in a direction along said path to locate said permanent magnet in said second position spaced away from said second end of said coil and when the electrical power to said coil is terminated, the magnetic field produced by said permanent magnet moves said plunger along said path in a direction to locate said permanent magnet in said first position near said second end of said coil,   said second end wall of said housing comprises an opening formed therethrough,   said support means being moveably supported in said opening of said second end wall of said housing,   said plunger comprises means for engaging said second end wall of said housing when said permanent magnet is moved to said second position for preventing movement of said permanent magnet beyond said second position,   a source of electrical power, and   a switch for connecting and disconnecting said source of electrical power to and from said electrical coil,   said source of electrical power and said switch being located outside of said housing,   said switch being the only means for connecting and disconnecting said source of electrical power to and from said coil.   
     
     
       16. The solenoid of claim 15, wherein: said opening of said surrounding wall is cylindrical in shape having a given diameter wherein the space between said second end of said coil and said second end wall is cylindrical in shape having a diameter substantially equal to that of said given diameter.   
     
     
       17. The solenoid of claim 15, wherein: said support means extends through said opening of said second end wall with an end extending beyond said second end wall when said permanent magnet is located in said second position,   said end of said support means when extending beyond said second end wall is unenclosed.   
     
     
       18. The solenoid of claim 16, wherein: said support means extends through said opening of said second end wall and with an end extending beyond said second end wall when said permanent magnet is located in said second position,   said end of said support means when extending beyond said second end wall is unenclosed.   
     
     
       19. A solenoid, comprising: a housing comprising a cylindrical wall having a cylindrical opening extending between first and second ends with first and second end walls coupled to said first and second ends of said cylindrical wall respectively forming an enclosed cavity,   an electrical coil fixedly located in said enclosed cavity of said housing,   said electrical coil having a central opening extending therethrough with said central opening having a central axis,   said electrical coil having first and second ends,   said second end wall of said housing being spaced from said second end of said coil,   a rod formed of a material capable of being magnetized when located in a magnetic field,   said rod being fixedly located in said central opening of said electrical coil and having an end extending to a position near said second end of said electrical coil,   a plunger comprising a permanent magnet and support means for supporting said permanent magnet for movement in the space between said second end of said coil and said second end wall of said housing along a path in line with said central axis in opposite directions within said enclosed cavity to locate said permanent magnet in first and second positions such that when electrical power is applied to said coil, a magnetic field is produced by said coil which moves said plunger in a direction along said path to locate said permanent magnet in said second position spaced away from said second end of said coil and when the electrical power to said coil is terminated, the magnetic field produced by said permanent magnet moves said plunger along said path in a direction to locate said permanent magnet in said first position near said second end of said coil,   said second end wall of said hosing comprises an opening formed therethrough,   said support means being moveably supported in said opening of said second end wall of said housing,   said plunger comprises means for engaging said second end wall of said housing when said permanent magnet is moved to said second position for preventing movement of said permanent magnet beyond said second position,   said plunger being the only movable means in said cavity of said housing of said solenoid.